The purpose of this research is to examine mother/child attachment relationships in families with affectively ill mothers (unipolar depression and bipolar illness) and well mothers. Previous research suggests that maternal responsivity and sensitivity to a child's signals underlies a secure attachment relationship. Much of attachment research has been based on normal (low-risk) samples. This high-risk sample of affectively ill mothers and their children provides an opportunity to answer important questions about the organization of normal and atypical behavior. Attachment assessments and behavioral observations are made as part of the longitudinal study (MH 02144). Analysis of these data revealed that children with an affectively ill mother were more likely to be insecurely attached than children of well mothers. This relation was particularly strong for the children of bipolar mothers. Affective behavior expressed by both mother and child was strongly related to attachment security. For example, there is a striking link between mother's downcast negative mood and insecure attachment.